This invention relates to a navigation-monitoring apparatus for detecting the position of a ship sailing through a narrow course, for example, a canal.
Where a ship sails through a narrow course such as a canal, an experienced pilot generally guides the ship, while visually confirming her route. When a clear view is obtained due to good weather conditions, the sailing of a ship through the canal under the guidance of a pilot raises no problem. However, when, for example, dense fog hangs over the course to obstruct the view, then a ship encounters considerable difficulties in clearing through the canal. In such case, the ship has to slow down her travelling speed for safety, or the canal itself must be closed to all shipping.
In recent years, shipping traffic has increased, and an increasing number of ships run through canals. Therefore, a strong need exists for a device which will ensure their safe and speedy passage through the canal in order to reduce the cost of navigation.